Cosmetic powders are currently available in loose and pressed form. The majority of these powders, face powder, blusher, eyeshadow etc., are used in pressed form. This form of the product is very practical since it is easy to carry along and can be used whenever needed for touching-up.
The main properties of a pressed powder are: easy powder release without dustiness, good skin adhesion, and a strong cake which does not crumble, break or cake-up.
In order to achieve all of these characteristics, the present pressed powder formulations contain a blend of several ingredients, each chosen for their specific quality.
The major constituents of a regular shaded pressed powder are talc and color; all other ingredients being used to achieve compressibility. Binding is a special property inherent to a pressed powder formulation. Most powder constituents found in formulations are not "binding" in themselves and therefore other agents such as metallic stearates, kaolin, and fatty materials are used as additives to insure proper adhesion and compressibility. Fatty materials, such as mineral oil or fatty alcohols, are used in liquid form to aid in binding, improve skin adhesion and reduce cake dustiness.
In frosted products, mica and titanium dioxide coated mica (pearlescent materials) are the major powder constituents. In order to compress these materials, a large portion of about 20-40 percent of the composition is additives. Such large amounts of non-pearlescent ingredients reduce the "frosty" effect of the product.
In U.S. Pat. No. 1,996,168, 1 to 5% of beeswax or synthetic wax and a small amount of soap are combined in melted form with mineral oil and heated. After cooling the mixture, powdery materials such as talc are added. No mention is made of compressing this powdery product. In U.S. Pat. No. 1,707,684, olive oil is used as a waterproof binder for powder in loose form.
U.S. Pat. No. 3,300,387 discloses a pressed powder consisting of an anti-perspirant coated with 5-15% of a water-soluble wax-like material such as PEG and its methoxy derivatives mixed with a powder base and an oily binder such as mineral oil, lanolin, vegetable oils and isopropyl esters of fatty acids.
The pressed powders of U.S. Pat. No. 3,800,034 contain binders such as gums, cellulose derivatives, gelatin, lignin, PVP, PVA and a complex magnesium silicate and lubricants such as metal stearates, liquid paraffin, fatty alchols, fatty acids and oils. U.S. Pat. No. 4,279,890 also employs metal stearates as binder and lubricant in pressed powders. Prevention of cracking in pressed powders was provided in U.S. Pat. No. 4,305,931 by incorporating a hydroxypropyl-etherified glycolipid ester.
Manufacturing of a pressed powder is long and tedious. It involves blending of all dry powder ingredients, wetting the blend with the liquid fatty material with subsequent balling up of the powder. In order to break up the powder balls and to achieve a uniform liquid distribution within the powder, it must then go through a micropulverization process. The inability to hold a shape after compression may vary with the chemical origin of the binding agent and the percentage utilized in the pressed powder formulation.